Craft & Design Workshop
“Hinge Technique” Acrylic Box Construction

If you’ve ever tried to build a box from clear acrylic, you know how hard it can be to get good-looking joints between the panels. The folks at TAP Plastics have gotten pretty good at it, but even they admit that the basic slab-joint method “will not produce museum grade products.”

This video was produced by the German firm Serrox Technischer Handel, which sells plastics fabrication products. Unsurprisingly, it promotes a number of their specialized products, but I think the underlying process—which has very much to recommend it over the slab-joint method—could probably be adapted to do without them. It’s a bit difficult to describe in words, so you may save some time just watching the video, but I’ll give it a shot:

  1. 90-degree V-grooves are cut almost all the way through a rectangular sheet of acrylic—one groove parallel to and equidistant from each side.
  2. Strips of solvent-proof tape are applied to the ungrooved side of the plastic—one strip centered over and all the way along each groove.
  3. The plastic is bent and snapped at each groove. The strips of tape have become hinges.
  4. The four small squares of waste plastic in the corners are removed, and a couple bits of interfering tape are cut away with a razor.
  5. The sides of the box are folded up along the hinges. The tape has kept everything exactly in place, so all the miters line up perfectly. Strips of tape are applied at the four corners to hold everything in place.
  6. Solvent cement is applied along the inside of each mitered edge. When it sets, the tape is removed, and the box is complete.

The key process is cutting the 90-degree V-grooves, for which Serrox sells a special V-groove circular sawblade. I am led to wonder, however, if it couldn’t be done just or almost as well with a V-groove router bit, as long as you took steps to keep the cut from getting too hot…

29 thoughts on ““Hinge Technique” Acrylic Box Construction

  1. Yes Sean it can be done with a 90 deg. Router bit. I do it this sway all the time on the Shopbot but I use just plain old Blue painters tape. Really NO Speciality tools or Chemicals are required to do this.
    You also do the same thing but leave your cut depth shallower and use a heat strip to bend the acrylic into place. Which leaves you with a nice smooth rounded one piece feel.

  2. That’s a neat technique, and no mistake…

    but i really doubt that from setting up the cuts on the $1000+ radial saw system [not shown] to the last bit of solvent evaporation is a “make a box in 5 minutes” project.   and if one can knock-out/remove the unneeded corner pieces so easily, doesn’t that mean that the hinge joints that are part of the project are rather weak points too?

    1. You’ve got it wrong – those aren’t hinge joints once the plastic has snapped. They only hinge on the tape until the final stage when the plastic dissolving solvent is applied and then the sides fuse to the bottom through a plastic weld.

    2. You’ve got it wrong – those aren’t hinge joints once the plastic has snapped. They only hinge on the tape until the final stage when the plastic dissolving solvent is applied and then the sides fuse to the bottom through a plastic weld.

  3. Great idea until I got a quote back from the distributer for the blade…  $680 for ONE blade shipped to the US.  No thanks…

  4. Great idea until I got a quote back from the distributer for the blade…  $680 for ONE blade shipped to the US.  No thanks…

  5. Great idea until I got a quote back from the distributer for the blade…  $680 for ONE blade shipped to the US.  No thanks…

    1. If you have a table saw you can get a Magic Molder head with a 45 degree Vee insert plug for about half that.  I’ve seen these around for years, but never tried one.

      Or you can set a zero kerf table saw blade at 45 degrees and make two passes in opposite directions.  I would definitely use a sled or miter gauge to feed the material for the second pass.  If you push it along the fence it would likely buckle up, catch the back end of the blade,  and throw your workpiece back into your gut

      http://www.bladesllc.com/magic-molder-heads.html

    2. If you have a table saw you can get a Magic Molder head with a 45 degree Vee insert plug for about half that.  I’ve seen these around for years, but never tried one.

      Or you can set a zero kerf table saw blade at 45 degrees and make two passes in opposite directions.  I would definitely use a sled or miter gauge to feed the material for the second pass.  If you push it along the fence it would likely buckle up, catch the back end of the blade,  and throw your workpiece back into your gut

      http://www.bladesllc.com/magic-molder-heads.html

      1. Assuming you were working with a relatively thin piece of acrylic, wouldn’t the kerf of a normal blade be enough to cut the other half of the 45*?

        1. Twiek, I believe it would, but my kerfless blade is only about an 1/8″ wide, so your material would have to be around 3/32″ would be about the max thickness .  But using this idea, you could use a dado stack and cut much thicker material. 

          I might have to try this:  I think I have some acrylic in the shop, have some blue tape that worked fine with solvent based automotive finishes, and know I have a dado stack.  I  just need some of that capillary action adhesive.  A single pass with a dado cutter would avoid having to try to cut a floppy workpiece, and make it much faster. 

        2. Twiek, I believe it would, but my kerfless blade is only about an 1/8″ wide, so your material would have to be around 3/32″ would be about the max thickness .  But using this idea, you could use a dado stack and cut much thicker material. 

          I might have to try this:  I think I have some acrylic in the shop, have some blue tape that worked fine with solvent based automotive finishes, and know I have a dado stack.  I  just need some of that capillary action adhesive.  A single pass with a dado cutter would avoid having to try to cut a floppy workpiece, and make it much faster. 

  6. Point 4: the excess tape is not cut away but merely sliced along one edge and then but they stay as flaps of tape that are later used in your step 5 to hold the four corners in place.

  7. The V-Groove Blade cut is the show stopper. It would probably cost a couple of hundred. And where would you get it? With a bit of dicking around you could probably set up a table saw at 45 degrees to make the grooves in two steps, but it would take a lot longer than 5 minutes, but once you figured out the process it could go pretty quick.

  8. You could definitely do it with a v groove router bit. That’s how I cut lots of miter joints on my cnc. On baltic birch and acrylic. I never thought of using the tape though. I’m definitely going to try their method.

    1. Hi! I’d like to look into this. Can you give me some more info on what type of pop up ads you were seeing?

  9. I watched the video before you posted your comments and didn’t listen to it as I assumed it was in German (and my last class in college German ended in 1974). There were quite a few frequent and annoying ads.

    Thanks for the router idea! I will give it a try with a V-Groove bit though I wish I had some idea what kind of tape would be solvent-proof. I need to make 12 acrylic boxes (wedding centerpieces for a daughter – the acrylic boxes to go inside wooden boxes to contain florist foam, flowers, water, lantern and LED candle), so I think I will soon have the chance to experiment with a few different kinds of tape.

    My plan for cool running will just be to cut a bit at a time and rest between cuts with my plunge router using an edge guide. We will see how it goes after I make a trip to the big box store for some acrylic sheets. The colored stuff appears to be about twice as expensive as the clear acrylic online.

  10. 1. Where may these products be purchased?

    2. What about the products mechanical dimensions
    (i.e. Sawblade) and chemical specifications?

    3. Why two different angles (i.e. 90 and 96 deg.) of
    cut of the sawblades?

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I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I am a long-time contributor to MAKE magazine and makezine.com. My work has also appeared in ReadyMade, c't – Magazin für Computertechnik, and The Wall Street Journal.

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